Flux valve



July 2, 1946. M. c. DEP-P ETAL FLUX VALVE Filed April 15, 1945 3 Sheets-Sheet 1 July 2, 1946. MQC. DEPP ETAL 2,403,347

FLUX VALVE Filed April 15, 1943 5 Sheets-Sheet 2 FIG.9"

v IGJZ THEIR ATTO'RNEY FIG. 22

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M. C. DEPP ETAL FLUX VALVE Filed April l5, 1943 5 'Shefis-Sheet s FIG.2l.

IR TTORNEY Patented July 2 1946 FLUX VALVE Marlin C. Depp, Hempstead, and Caesar F. Fragola, Brooklyn, N. Y., assignors to Sperry Gyroscope Company, Inc... a corporation of New York Application April 15, 1943, No. 483,224

17 Claims. (Cl. 177-380) Our invention particularly relates to a flux valve or a device which is sensitive to an external undirectional magnetic field and will provide an output which in magnitude is approximately acosinusoidal function of the orientation of the device relative to the direction of the external field, and which output also has a. phase sense depending upon the position of the device in said field.

Flux valves ordinarily comprise a coreof permeable magnetic material having associated therewith a pick-up winding for supplying a voltage output and an exciting winding which is connected to a source of pulsating or alternating current energy to provide a pulsating or alternating flux in the core. In operation, the voltage.

induced in the pick-up winding by the flux of the external field is of a double frequency value. That is to say, the component of the, voltage output of the valve which is induced therein by interaction with the external field, is of a frequency equal to twice that of the source of alternating current employed in energizing the primary or exciting windings. It is very desirable to eliminateany component in the output voltage of the flux valve which is of the fundamental frequency or the frequency of the source of energy used in windings may closely approximate a sine curveor may be sinusoidal in form. When acomponent is present corresponding in frequency to the exciting current, the output of the valve will be distorted thereby and the valve output will not be'a simple cosinusoidal or closely approximate c'osinusoidal function of the position of the valve with respect to the direction of the external field. i

Itis therefore the principal object ofour invention to provide a flux valve, the parts of which are so correlated, constructed and ar-- ranged as to provide a signal voltage output in which substantially no component corresponding in frequency to that of the exciting current is present or any component due to direct linkage with the exciting circuit.

More particularly, it is an object of our invention to provide a flux valve in which the fundamental flux or the flux induced in the core thereof by the'exciting magneto-motive force will be controlled in its linkage with the secondary or pick-up winding thereof.

It is a further object to provide a flux valve' of the oppositely flowing fluxes with said pick-up winding.

Another object resides in providing a flux valve of the character above set forth in which the pick-up winding and the magnetic shunt may be relatively moved in order to cancel out in the pick-up winding any voltage component corresponding in frequency to the fundamental or the frequency of the exciting source or harmonics thereof otherthan the double frequency, second harmonic.

It. is a still further object of our invention to provide a flux valve in which the exciting flux is caused to flow through the horns or collector rings whereby toelfect demagnetization thereof.

With these and other objects in view. our inventlon includes the novel constructions, correlation and relative arrangement of elements described below and illustratedin the accompanying drawings, in which:

Fig. 1 is a plan view of one form of flux valve embodying our invention;

Fig. 2 is a plan view of a modification of Fig. 1;

' Fig. 3 is a fragmentary sectional view taken in about the plane 3-3 of Fig. 1;

Fig. 4 is a sectional view of Fig. about the plane 4-4 thereof;

Fig. 5 is a somewhat schematic plan view of a flux valve having a modified form and relative arrangement of windings;

6 is a fragmentary elevation view of the flux valve of Fig. 5; a I

Fig. 7 is a fragmentary elevation view of a flux valve conforming in construction to the valve of Fig. 5 but additionally illustrating a positioning means for the secondary or pick-up windings 1 taken in thereof;

Fig. 8 is a fragmentary sectional-view taken i about the plane 8-8 of Fig. '7;

Figs. 9 and 10 each show one manner in which the pick-up winding and magnetic shunt of a flux valve may be relatively adjusted;

pick-up winding associated with said core, and

magnetic shunt means for controlling the linkage Fig. 11 illustrates a modification;

Fig. 12 is a schematic showing of a flux valve having a modified form of magnetic shunt;

Fig. 13 is a side elevation view of a flux valve embodying the construction represented in Fig. 12;

Fig. 14 schematically illustrates a further for of flux valve having a magnetic shunt of the character illustrated in Figs. 12 and 13;

Fig. 15 is a side elevation view of a flux valve embodying the construction represented in Fig. 14;

Fig. 16 illustrates a modification;

Fig. '17 is a plan view of a flux valve having radially extending legs but embodying flux linkage control means;

18is a sectional view taken in about the plane l8-l8 of Fig. 17, the pick-up winding being schematically represented;

Fig. 19 is a plan view of a flux valve generally similar in form to ,that of Fig. 17 but having a modified correlation of parts;

Fig. 20 is a sectional elevation view taken in about the plane 20-20 of Fig. 19;

Fig. 21 is a sectional elevation view taken in about the plane 2l-2l of Fig. 19;

Fig. 22 is a plan view of a still further modified form of flux valve;

Fig. 23 is a fragmentary sectional view taken in about the plane 23-23 of Fig. 22 but showing the flux valve mounted in a casing; and

Fig. 24 illustrates in perspective a modified unitary construction of the respective legs and their associatedcollector rings. 3

Referring first to 'Figs. 1 through 4 and particularly to Fig. 1, the flux valve of the embodiment of our invention therein illustrated comcore sections, each of which is arranged generally in the form of a polygonal frame such as the closed triangular frame illustrated in Fig. 1. In other words, the upper section 2 of the core I will comprise the leg portions 4, 5, and 6, each arranged to lie along one side of a closed triangular frame. Likewise, the lower leg 3 of the core will have similarly arranged leg portions. In practice, the leg portions 4, 5, and 6 may form an integral unit, or the triangular core may be composed of thin, fiat strips connected together at the apexes of the triangle. Additionally, the leg portions of the generally triangular core may each lie along the sides of a closed polygonal or triangular frame with the ends thereof lying in close but spaced relation to each. other at the apexes of the figure formed thereby.

In Fig. 4, we have shown the relative arrangement of core parts and windings which alone may constitute a-flux valve but as shown comprises one leg portion of the flux valve of Fig. 1. In the embodiment shown in Fig. 4, both ends ofthe core sections ,2 and 3 are connected to the core of'exciting means indicated generally at 1. These exciting means comprise a core 8 carrying thereon the winding 9, the core 8 being interposed between the core portions 2 and 3 .to form a closed magnetic path therebetween and adjacent the ends thereof. On one core section 2 or 3, herein illustrated as section 3, is mounted the secondary or pick-up winding I0. 'With the secondary winding associated with the leg 3, a shunt II of magnetic material 'is preferably associated with the other leg 2 and is adapted to extend into close .proximity to the pick-up coil Ill. In operation, the coils 9 of the exciting means are connected across a source I: of pulsating or periodically varying, preferably alternating, current. By virtue of the relative arrangement of the excitingcoils 8 at each end of the core structure, fluxes are caused to flow in each core leg 2 and 3 and in relatively opposite directions in each for instantaneous values thereof as represented by the arrows in Fig. 4. For example, flux will flow toward the centerIof the upper core section 2', through the magnetic shunt H,

Al. and link with the pick-up coil 10, flowing in relatively opposite directions with respect thereto and toward the outer ends of the lower core section 3. The direction of flow of these fluxes will, of course, alternate with each alternation of the exciting current. However, the shunt II will serve closely to control the linkage of the bucking, exciting fluxes with the pick-up windingv l0, and since the voltages induced by the exciting fluxes in the pick-up winding will be opposing each other, the winding Ill may be shifted lengthwise of core 3 and relative to shunt II in order to balance out these voltages and thereby substantially eliminate any component in the output voltage of the winding III which is induced therein by the primary or exciting fluxes linking therewith.

In practice, the output of the coil It) may be analyzed and the coil shifted in the above-described manner until the undesirable harmonics and mainly the fundamental or the component of a frequency of that of source 12 is substantially eliminated. whereupon, thecoil may be fixed in this position in any suitable manner such a by applying any suitable means such as sealing compound or varnish thereto to hold it in adjusted position.

It will be understoodthat in Fig. 1 each 'rela- I tively angularly disposed leg thereof may conform in construction substantially to that illustrated in Fig. 4, and flux collectors or horns l3 may be connected to the upper and lower core sections and at the apexes of the triangle formed thereby. If collectors I3 are employed, the ends of the upper and lower of each pair are preferably connected together in the manner shown in Fig. 3. The ends of the upper and lower collectors l3 are firmly connected together, but a closed magnetic path therebetween is revented by the use of a spacer l4. Preferably, the spacer as a whole comprises portions having magnetic and non-magnetic properties, as indicated at Ma and Nb, respectively, in order that only a' small gap in the magnetic circuit i provided'thereby but a gap of a length suflicient to prevent shortcircuiting of the magnetic path through the leg portions 4, 5 and 6, etc., of the core of the valve.

If desired, the collector rings l3 may be eliminated in a flux valve having a core arranged in the form of a closed or substantially closed triangular frame, as shown in Fig. 2.

In Figs. 5 and 6, we have shown a flux valve having flux linkage control means generally similar to that hereinabove described and which will '6 and comprises upper and lower core sections I5 and I6 similar to the core sections 2 and 3 of Fig. 4. However, inthis embodiment, the ends of the laterally spaced sections l5 and I6 are connected together by spacers H of 'magnetic material to form a closed magnetic circuit. Preferably, a shunt l8 generally similar to shunt ll extends from the core section l5 and into close proximity to the pick-up winding l9 mounted on core section 5. The exciting windings in this embodiment, however, are mounted on the upper core leg 15 instead of being interposed between the core legs as shown in Fig. 4. The exciting windings are adapted to be connected across the source of pulsating or alternating current I! and'comprise'oppositely wound windings 20 and ward each other and through the shunt l8 and thence outwardly in the core section l6 toward both ends thereof. As hereinbefore indicated. if the pick-up winding I9 is properly adjusted lengthwise of thecore section It with respect to shunt l8, the opposing voltages induced therein by the primary or exciting flux will be substantially balanced, and no component thereof will appear in the output of the flux valve.-

It will be understood that each of the core legs 22,23, 24, 25, 26, and 21 of the flux valve of Fig. 5 embody the construction shown in Fig. 6, and the piek-up windings on diametrically opposed legs or legs lying on opposite sides of the hexagonal frame may be connected together to provide a threephase voltage output from the valve or, more accurately stated, an output comprising three signal voltages "adapted for use with Selsyn type receivers such as repeater motors or signal transformers. In this case, if the secondaries or pickup windings, which are connected together as above described,.are so connected that any voltages induced therein-by the exciting flux are opposed, then it is merely necessary to adjust one of each pair of connected pick-up windings relative to its associated shunt in order to balance out fundamental voltage components in that phase of the output of the valve.

- Adjustment of the pick-up windings of the flux valve may be accomplished as above described, but instead ofsealing them in adjusted position as hereinbefore indicated, a clamping means may be provided for this purpose as shown in Figs. 7 and 8. In these figures we have shown the pickup coil i9 as being closely embraced by a clamp 28. The clamp includes a laterally ofiset portion 29 (see Fig. 8) which is provided with a slot therein, a set screw 30 extending through said slot and into the supporting base 3| for the flux valve. When the winding 19 has been properly adjusted to eliminate so far as possible the undesired fundamental frequency component, it may be-thereafter rigidly retained in adjusted position merely by tightening the screw 30.

In Figs. 9 and 10, we have shown flux valves or devices which may constitute one of the legs of a multi-legged flux valve, wherein means are provided for effecting relative movement between the pick-up coil and the magnetic shunt for controlling the fl-ux linking with the pick-up coil. In Fig. 9, the core comprises the spaced core sections or members 32 and 33. In this embodiment, the shunt M is formed by bending the core memher, which is preferably formed of thin strip, permeable materiaL. reversely back upon itself and then substantially at right angles to the reveisely bent portion, as illustrated. The exciting windings 35 disposed between the core strips -32 and 33 and adjacent both ends thereof are strip 33, and adjustment thereof lengthwise of,

the stripand relative to the shunt 36 may be effected by the set screw 3'! which passes through an opening in support 38 therefor and engages a threaded opening in an ofiset 39 of the spool to carrying the secondary winding.

Likewise, as shown in Fig. 10, the shunt may be movably supported rather than the pick-up winding. In. this embodiment. the lower core strip 4| carries the pick-up coil 42 while the shunt R3 is s'lidably mounted upon the upper core strip 44. A set screw 45 mounted in a supporting bracket 46 engages a threaded opening in the shunt 43 and serves to adjust the shunt lengthwise of the flux valve coreand relative to the pick-up winding 42. A helical spring (not shown), in the constructions shown in Figs. 9 and 10, may be interposed between the supporting brackets 38 or 46 and the movable member, that is, the spool 40 or the shunt 43.

In order to provide a greater output from the flux valves of the foregoing characters, they may be modified in the manner shown in Fig. .11 wherein pick-up coils are associated with both upper and lower core strips. Although the shunt 34 is therein illustrated as relatively fixed, itmay be movable, as above described. On the lower core strip is mounted a pick-up winding 25c which may be initially adjusted lengthwise thereof and relative to the shunt 34 and then fixed in position in any suitable manner. Pick-up windings 36b and 360 are mounted on the upper core strip 32 on opposite sides of shunt 36. The windings 36b and 38c are so arranged that the voltage components induced therein by the exciting flux are in opposition and tend tocancel each other. These windings are connected with windings 36a, in which the opposing fluxes induce opposing voltages therein, and in such manner that the double frequency, signal voltage induced in these windings through reaction with an external field are additive. Balancing of the resultant voltage components from. windings 3th and 360, induced therein by the exciting fluxes, against the similarly induced, resultant voltage components in winding 36a may be achieved by relatively adjusting winding 36a and shunt 36 whereby substantially to eliminatethe undesired voltage components while providing a greater output as compared to the units shown in Figs. 9 and 10, for example.

As illustrated in Fig. 12, the core of the flux valve may comprise a single strip or a laminated strip d? on which are mounted exciting windings 48 and 68, arranged to provide oppositely flowing fluxes for any instantaneous value thereof in the core M. A secondary or pick-dip winding 58 may be mounted over the exciting winding and. in this instance, an annular shunt M of magnetic material may be slid over the pick-up winding and adjusted lengthwise of the core and relative to the pick-up winding to control the exciting flux linking with the pick-up winding. The appearance of this formof flux valve is shown to better advantage in Fig. 13. However, it will be understood that theshunt functions to control the flux linking with the pick-up winding in substantially the same manner as the shunts hereinbeiore described.

In Figs. 14 and 15, we have shown a form of flux valve having a shunt of the general characpath therebetween. The exciting windings 55 and 5d are arranged in the same manner as windings 68 and $9 of Fig. 12 to provide oppositely flowing exciting fluxes in "the core strip 7 53 at any given instant. A shunt which preferably extends entirely about both core strips and their associated coils is movable lengthwise thereof to provide control over the linking of the exciting fluxes with the pick-up winding 95.

In Fig. 16, we have shown one manner in which a flux valve having a shunt of the character illustrated in Figs. 14 and 15 may be modiiied to provide a greater output. In this instance, the exciting coils 55a and 56a are mounted between the strips 52 and 53 and preferably adjacent the ends thereof, while the pick-up winding 95a, is arranged with the convolutions thereof encircling both strips 52 and 53. Shunt 51 preferably surrounds the pick-up coil. The exciting coils are arranged to produce opposing fluxes in each strip 52 and 53. Hence, due to the association of pick-up winding 95a. with both core stripsv 52 and 53, the voltage component induced therein by interaction with an external field will be much greater than in 'the pick-up coils of, for example, the units illustrated in Figs. 14 or 15. Furthermore, balancing of the opposing voltage components therein due to the exciting fluxes may be-eflected by adjustment of shunt 51 as hereinbefore described.

In Figs. 1'7 and 18, we have shown a flux valve in which the respective core legs are relatively angularly arranged in radially extending relation. However, excitation of the core legs and control over the flux linking with the pick-up windings is effected substantially in the same manner as hereinbefore described in connection with Fig. 4. In this embodiment of our invention, each upper and lower, spaced core sections GI and 62, shown in Fig. 18, comprise the radially extending core legs 58, 59 and 60. The variouslegs of the upper core section or the lower core section, respectively, may be formed integral or may comprise a plurality of core strips which are connected together at the center of the valve.

In the embodiment illustrated, the core comprises integral upper and lower leg sections, respectively, the lower thereof having a pick-up winding 63 mounted thereon and the upper being provided with a magnetic shunt 64 for controlling the exciting fiux linking with the pick-up winding. An exciting coil 65, mounted on a core 66 which is interposed between the upper and lower core sections at the center of the valve, serves to provide an exciting flux flowing in all leg sections.

Furthermore, in the form of this embodiment of complete elimination of a fundamental compo nent in the output thereof may be effected by adjusting the position of the pick-up windings I 63 relative to their associated shunts. Alternatively, of course, the shunts may be movably mounted to achieve the same result.

Furthermore, with an arrangement of exciting windings as disclosed in Fig. 17, those at the extremities of the collector rings will cause the flux to traverse not only the radially extending core portions but also the collector rings, where- 8 by to prevent permanent magnetic polarization of the collectors due to the influence of some external magnetic field. i

A somewhat similar arrangement of core parts is shown in Fig. 19 but, in this embodiment, we prefer to employ but a single exciting winding 65 arranged in a similar manner to that above described in connection with Figs. 17 and 18 and at the center of the flux valve. Non-magnetic spacers III are interposed between the upper and lower leg sections 90 and 9| of the core and collector rings 92 at theouter ends of the leg portions while magnetic shunts II provide a closed magnetic path between the collector rings at the extremities thereof. In this embodiment, the

v secondary or pick-up windings I2 extend about the upper and lower core sections of each leg.

' By virtue of this construction, as in the embodlment of our invention shown in Figs. 17 and 18, the exciting flux flows and reverses in direction. if an alternating exciting current is employed, throughout the collector rings as well as in the radial leg portions whereby to effect demagnetization of the collectors.

Figs. 22 and 23 disclose a flux valve which is quite similar to that shown in Fig. 19, but, in this form.-the exciting windings are mounted on upper and lower radially extending legs of the core. The legs of the upper and lower core sections may be integral or separate strips may be used and clampedtogether at the center oi! the valve as illustrated. The upper leg section I3 has an exciting winding 14 mounted thereon, and the lower leg section 15 has an exciting winding I6 mounted thereon. These windings may be connected to provide a flux flowing in opposite directions in the cores I3 and 15, respectively, for any instantaneous value so that the pick-up winding 11 which surrounds both core legs will have induced therein voltage components of fundamental frequency which are of substantially equal and opposite magnitudes. In this manner, therefore, the fundamental maybe eilectively reduced or substantially eliminated in the output of the flux valve. In the particular construction of the flux valve illustrated in Figs. 22 and 23,the upper core section comprising the leg 13' is mounted upon a spacer I8 of magnetic material at the center of the valve which through the medium of the bolt 19, washers and nut serves to hold the two core sections I3 and I5 together and in spaced relation. A spacer 8| of non-magnetic material may be interposed between the upper and lower core sections in the zones of connection thereof with collector rings 62 at the outer ends of the core legs, while spacers 83 of magnetic material may be employed to connect the collector rings at the extremities thereof and provide a closed magnetic path therebetween.

Furthermore, to provide a stronger flux valve construction, we may interpose a strip or strips 84 of suitable material, preferably insulating material such as Bakelite between the core legs and the exciting windings which function to reinforce the relatively thin core members I3 and I5. In practice, the core and the windings thereon may be supported within a casing 85, preferably of non-magnetic or electrical insulating material, as indicated, the central section of the valve being supported upon the annular boss 86 formed in the based the casing and the collector rings resting upon an annular shoulder 81 adjacent the outer wall of the casing. Provision may be made in the annular shoulder 81, as by forming recesses 88 therein. to receive the lower end of the clamping screws and nuts employed in fastening the collector rings, core sections and shunts 83 together.

The respective upperand lower core strips and their associated collector rings of each leg of a multi-legged flux valve may be formed as a unit for incorporation in the complete valve structure. In this way, each unit may be separately tested and rated. and matching units employed in each valve. Such a unit is shown in Fig. 24 wherein the unit is generally similar in construction to one of the legs of the valve of Fig. 22. In the embodiment illustrated, the upper and lower' core strips '6 and 91, respectively, have collector rings 96a and 91a formed integrally therewith. Exciting windings 98 and 99 are mounted on the strips 96 and 91, respectively, and may be connected as described in connection with theexciting windings of Fig. 23. A pick-up winding mo is mounted over both core strips and exciting windings. and the strips are fastened together in fixed, spaced relation by spacers llli, preferably of magnetic material. These spacers are similar to grommets, that is, they are hollow having shoulders thereon serving to. space the strips while the ends may be beaded over', as shown, to provide a unitary structure. These spacers may be of nonmagnetic or partially of non-magnetic material to provide a small air gap. For assembly purposes, the casing may be provided with upstanding pins adapted to be received respectively within the hollow spacers whereby accurately to position the various units relative to each other in the complete multi-legged flux valve assembly. The various units, of course, may be connected to provide a polyphase or polycircuit output, such as three signal voltages.

It will be understood that the various correlation of parts herein described, whereby control over linking of the exciting flux with the pick-up windings is efi'ected, may be employed in many forms of flux valves whether they comprise a single leg or are of the multi-leg type.

Since many changes could be made in the above construction and many apparently widely difi'erent embodiments of thisinvention could be made without departing from the scope thereof, it is intended that all matter contained in the above descripion or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a devicesensitive to an external magnetic field and adapted to supply signal voltage outputs dependent in magnitude upon the D0511 tion thereof relative to the direction of said field, a core of permeable magnetic material, means for producing periodically varying exciting fluxes flowing in opposite directions for any instantaneous value thereof in said core, a. pick-up winding associated with said core, and common means extending into closely spaced relation to the pick-up winding in a central zone substantially midway between its ends for controlling the linking of the exciting fluxes with said pickup winding.

2. In a device sensitive to an external magnetic field and adapted to supply signal voltage -outputs dependent in magnitude upon the position thereof relative to the direction of said field, a core comprising a pair of core members of permeable magnetic material, means for producing periodically varying exciting fluxes. flowing in opposite directions for any instantaneous value thereof in each of said core members, a

pick-up winding :atssociated with one of said core.

members, and -means extending into closely spaced relation to the exterior of said pick-up winding in a central zone substantially midway between its ends for controlling the linking of tion thereof relative to the direction of said fleld,

a core of permeable magnetic material forming a substantially closed path for the flow of flux therein, means for producing pulsating exciting fluxes mowing in opposite directions for any instantaneous value thereof in zones of said core, a pick-up winding disposed about said core and in said zones, and means extending crosswise of said closed path and in closely spaced relation to the exterior of said pick-up winding in a central zone substantially midway between its ends for controlling the linking of the exciting fluxes with said pick-up winding.

4. In a device sensitive to an external magnetic field and adapted to supply signal voltage outputs dependent in magnitude upon the position thereof relative to the direction of said field, a core of permeable magnetic material, means for producing periodically varying exciting fluxes flowing in opposite directions for any instantaneous value thereof in said core, a pick-up winding associated with said core, a shunt of magnetic material for controlling the linking of exciting fluxes with said' pick-up winding, and manually adjustable means forrelatively moving said shunt and pickup winding. 7

5. In a device sensitive to an external magnetic field and adapted to supply signal voltage outputs dependent in magnitude upon the position thereof relative to the direction of said field, a core of permeable magnetic material,

means for producing periodically varying exciting fluxes flowing in opposite directions for any instantaneous value thereof in said core, a pick-up winding associated with said core, and common means extending into closely spaced relation to the exterior of said pick-up winding in a central zone substantially midway between its ends for controlling the exciting flux linking with said pick-up wind-ing, said flux control means and pick-up winding being supported at least initially in relatively movable relation.

6. In a device sensitive to an external magnetic field and adapted to supply signal voltage outputs dependent in magnitude upon the position thereof relative to the direction of said field, a core comprising a pair of core members of permeable magnetic material arranged in laterally spaced relation, means for producing periodically varying exciting fluxes flowing in oppo-- outputs dependent in magnitude upon the posi tion thereof relative to the direction of said field, a core of permeable magnetic material, means for producing periodically varying fluxes flowing in opposite directions for any instantaneous value thereof in said core, a pick-up winding associated tral zone substantially midway between the ends thereof for controlling thelinking of the exciting fluxes with said pick-up winding.

" 8. A flux valve sensitive to an external magnetic field and adapted to supply signal voltage outputs dependent in magnitude on the position thereof relative to the direction of said field comprising a pair of cores of permeable magnetic material each arranged substantially in the form of a closed polygonal frame, exciting means disposed adjacent each end of the sides of said frame for producing pulsating fluxes in adjacent frame sides flowing for any instantaneous value thereof in opposite directions in each frame side, pick-up windings associated with the frame sides, and

means disposed intermediate the lengths of said frame sides for controlling the flux linking with said pick-up windings.

9. A flux valve comprising a pair of cores of permeable magnetic material each including relatively angularly arranged leg portions, respective legs of each core being disposed in spaced relation to each other, and the legs of each core having collector'members associated therewith, corresponding collector members of both cores having means adjacent the ends thereof form-ing closed magnetic paths therebetween, means for producing a pulsating fluxflowing through both the legs and collector members, and pick-up windings associated with said core legs.

10. A flux valve comprising a pair of cores of permeable magnetic material each including relatively angularly arranged leg portions, respective legs of each core being disposed in spaced relation to each other, and the legs of each'core having collector members associated therewith, corresponding collector members of both cores having means adjacent the ends thereof forming closed magnetic paths therebetween, means for producing a pulsating flux flowing through both the legs and collector members and in instantaneously opposite directions in said legs, pickup windings associated with said core legs, and

-means for controlling the flux linking with said pick-up windings.

11. A flux valve comprising a pair of cores of i permeable magnetic material each comprising correspondingly angularly arranged legs having collector members associated with the ends thereof, corresponding legs and associated collector members being disposed in spaced relation but forming substantially closed magnetic paths at the ends of said'collector members and at the end of said legs remote from the collector members, means for producing a pulsating flux in said core legs, and pick-up windings associated with each of said core legs.

12. A device of the character recited in claim 3 v g2 odicallyvarying fluxes flowing in opposite direc-. tions for any instantaneous value thereof in said core, a pick-pup winding surrounding both of said exciting coils, and a shunt of magnetic material surrounding said pick-up winding in a central zone substantially midway between its ends.

14. In a device sensitive to an external magnetic field and adapted to supply signal voltage outputs dependent in magnitude upon the position thereof relative to .the direction of said field,

a core comprising a pair of core members of permeable magnetic material, means for producing periodically varying exciting fluxes flowing in opposite directions for any instantaneous value thereof in each of said core members, a pick-up winding associated with one of said core members, and a shunt of magnetic material surrounding both of said core members and said pick-up winding, said shunt extending about said pickup winding in a central zone substantially midway' between the ends of said winding.

15. In a. device sensitive to an external magnetic field and adapted to supply signal voltage outputs dependent in magnitude upon. the position thereof relative to the direction of said field, a core comprising a pair of core members of permeable magnetic material, means for producing periodically varying exciting fluxes flowing in opposite directions for any instantaneous values thereof in each of said core members, a pick-up winding surrounding both of said core members, and a shunt of magnetic material surrounding said coils mounted on one of said core members for producing periodically varying exciting fluxes flowing in opposite directions for any instantaneous value thereofin each of said core mem- :bers, a pick-up winding mounted -on the other of the said core members, and a shunt 'of magnetic material surrounding both core members, said shunt extending about said pick-up winding in a central zone substantially midway between the ends thereof.

17. In a device sensitive to an external magnetic field and adapted to supply signal voltage outputs dependent in magnitude uponthe position thereof relative to the direction of said field, a pair of core members of permeable magnetic material connected together at their ends to form a closed magnetic path, means for producing periodically varying exciting fluxes flowing in opposite directions for any instantaneous value thereof in each of said core members, a shunt of magnetic material disposed between said core members, a pair of pick-up windings mounted on one of said core members and on opposite sides of said shunt and connected to combine the voltage components induced therein by said exciting fluxes in bucking relation, and a third pick-up winding mounted on the other core member, said pick-up windings being connected together.

MARLIN C. DEPP. CAESAR F. FRAGOLA. 

